Method of reconstructing holograms using a reflected undiffracted beam as a reconstruction beam

Abstract

A plurality of holograms carrying equivalent information are arranged so that the undiffracted beam passing through the first hologram is used as a reconstructing beam to illuminate the second hologram, and the undiffracted beam of the second is used as a reconstructing beam for illuminating the third and so on to obtain a single bright image constituted by a plurality of perfectly overlapped images. Another embodiment of the invention employs a plurality of holograms carrying information corresponding to different parts of an object in which the undiffracted beam passing through the i-th hologram is used to illuminate the (i+ 1)-th hologram as a reconstructing beam.

I claim: 
     
       1. A method of reconstructing a holographic image on an image-focusing plane by focusing first-order diffracted beams from holograms comprising the steps of: preparing a plurality of substantially identical holograms of an object;   arranging said plurality of substantially identical holograms located in a plane with spaces therebetween which spaces are large enough to unobstructedly pass a first-order diffracted beam from each said hologram to an image-focusing plane;   impinging a reconstructing beam onto a first one of said holograms; impinging the undiffracted beam passing through said first one onto a second one of said holograms;   focusing a first-order diffracted beam from said first one onto the image-focusing plane;   repeating the steps of impinging the undiffracted beam from a prior one of said holograms onto the next succeeding one of said holograms and focusing the first-order diffracted beam from said prior one onto a focusing plane until the undiffracted beam impinges on the last one of said holograms, said first-order diffracted beams from holograms being focused in the same region of the focusing plane so that the images reconstructed by the diffracted beams from different holograms are substantially registered with each other, whereby a single image of increased brightness is reconstructed.   
     
     
       2. A method of reconstructing a holographic image as defined in claim 1 further comprising the steps of arranging the plurality of substantially identical holograms in parallel to each other with spaces therebetween which spaces are large enough to unobstructedly pass the first-order diffracted beam from one hologram to the image-focusing plane, and converging the first-order diffracted beams onto the image-focusing plane by use of converging lenses to form substantially identical focused images substantially registered with each other on the focusing plane. 
     
     
       3. A method of reconstructing a holographic image as defined in claim 1 wherein said holograms are substantially identical holograms, each of said holograms containing information corresponding to a plurality of different independently recorded colors in the object, and white light is used as said reconstruction beam impinged on the first hologram, whereby a multi-color image of increased brightness is reconstructed on the focusing plane. 
     
     
       4. A method of reconstructing a holographic image as defined in claim 3 further comprising the steps of arranging the color holograms in parallel to each other, impinging the undiffracted beams on the holograms at the same angle as that at which said reconstruction beam impinges on the first one of said plurality of substantially identical holograms, and converging the first-order diffracted beams onto the image-focusing plane by use of converging lenses to form substantially identical focused color images perfectly registered with each other on the focusing plane. 
     
     
       5. A method of reconstructing a holographic image as defined in claim 4 further comprising the step of passing each of said first-order diffracted beams from holograms through a spatial filter having an aperture of the size corresponding to the band width of the spatial frequency spectra of the object on the secondary focal plane and on the optical axis of said converging lenses.